Telephone-exchange system.



J. L. WRIGHT. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV.13, 1907.

Patented Jan. 26, 1915.

4 SHEETS-SHEET 1.

giwentoz "l Vi tn eases .1. L. WRIGHT. TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED NOV.13, 1907 1,1 26,1 73. Patented Jan. 26, 1915.

4 SHEETS-SHEET 2.

1.. L, WRIGHT. TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED Nov. 13, 1907.

1",.12 ,1 73', Patented Jan.26,'1915.

4 SHEETSSHEET 3.

Eli wen tor,

witnesses J'. L. WRIGHT; TELEPHONE EXCHANGE SYSTEM.

, APPLICATION FILED NOV.13, 1807. 1, 1 26,1 73, Patented Ja11-.26,191 5.

4 SHEETS-SHEET 4.

avwonto'c llhlllTlED JOSEPH LANE WRIGHT. or CLEVELAND, OHIO, assienon so ENGINEERING CORPORATION, 05 WASHING-TON, DISTRICT. OF CU-JIT1VIBI A CORPQRATIGN OF THE DISTRICT GE COLUMBIA.

TELEPHONE-EXCHANGE SYSTEM.

State of Ohio, have invented certain new and useful Improvements in Telephone-EX- change Systems, of which the following is a specification, reference being had therein to the accompanying drawing.

My invention relates to telephone ex change systems and particularly to semiautomatic systems in which a portion or all of the work of interconnecting subscribers is done by machines controlled by oper ators.

The object of the invention is to provide a convenient, economical and etlicient circuit of the sending or signal transmitting apparatus, and also-to simplify the mechanical parts of the signal apparatus.

The characteristic features of my invention are these: A series or sets of teeth, each set having teeth from 1 to 10, are arranged upona common shaft and springs adapted to be operated by the teeth are connected to corresponding push buttons before the operator. When any number desired has been set up by depressing the corresponding button, aset of associated relays are pulled up and locked on a battery circuit which includes a series of contacts controlled by teeth on disks or break wheels rotated synchronously with the number wheels and acting to cut oil the battery from the locking wires successively once in each complete rotation. One of these relays is a guard for the other, so that they must be unlocked in inverse order, that is, the last one first, in order to produce any efiect. The impulse wires from the push buttons pass through back contacts on the last relay and front contacts on the first relay in series With the 7 contacts I on the intermediate relays and off and so on at every revolution, one relay Application filed Hovem'ner 13, 19m.

Serial No. $32,933.

being cut oil and properly transferring the circuit to its proper strip of lreys until the I' n 0 I nrst relay lets go, disconnecting the sig= naling apparatus from the trunk wires.

l have illustrated inyinvention in the accompanying drawings as applied to a common battery system, in which the operato-r plugs into the trunk jack and sets up the switches by means 01" impulses from the sending machine. The push buttons used are preferably provided with latches and are interlocking so that the depression of any one push button in a strip releases any other that have been previously depressed that strip.

Eigure l in t is accompanying drawings is a diagram of a subscriber s line, of a trunk terminal and-an operators cord circuit for interconnecting them. Fig. 2 is a diagram embodying the circuits of my invention and includes the .operators sending apparatus. Fig. 3 is a diagram of a first selector, second selector and connector switch of the ordinary Strowger type. Figs. t and 5 are respectively front and end views of the sending machine. Fig. 6 is an end view of a modified form of the sending machine.

Referring to Fig. 1, A. is a subscribers station, equipped with apparatus usual in common battery systems, consisting of the transmitter, receiver, switch hook, ringer and condenser. From this substation the line wires 1 and 2 extend to the central oilice, Where they pass through the normally closed contacts of the cut of relay to the line relay hi and ground respectively. The relay is connected on the other side to main battery B and controls a signal lamp L, associated with the answering jack The answering jacks J are supposed to be grouped in a convenient manner together with their signal lamps L in front of the operators and when any line is calling it is intended that it shall be connected throw a trunlr jack J with trunk lines leadin a first selector In order to interconnect the line to trunk jacks, I provide a pair of plugs and P" having their tips and sleeves respectively connected. through the conductors ll t i-t, these conductors being separated liy I plug P has associated with it a supervisor Y lamp'LQ'controlled by the relays R and R The relay R is placed in series with the cut off relay M, when the plug is placed in the jack J and the relay R has its circuit closed through the subscribers telephone.

The calling plug P has three conductors which. I shall call the tip 10, ring ,1) and sleeve 19?, the ring in this case corresponding to the sleeve of the plug .P. When the plug is inserted ingthe trunk jack J the tip and ring are connected respectively with the 'jack springs j and j, while the sleeve 79- comes into contact with the thimble 7' connected through aresistance coil 7' to ground. This thimble connection is for testing, and also furnishes or completes the circuit of the cutofl relay R when-the plug is inserted. The .two relays 1B and R are associated together for controlling-the connection of the operthrough the wires 17 and ls when the plug is first inserted in {the answering jack, the circuitB, 19,17 and 18-and ground being then immediately closed by the relay R llin'gnp; The rela R therefore, pulls up, while the relay R which controls it remains denergized, and reldy'R in pulling up closes the two sides of the operators secondary cir- 3 cuit .with the receiiver in series therewith 1 .ontoithe wires 7 and8, and from there across the cord conductors3 and 4, enabling her to converse with the calling subscriber. i-li Theprimary a" is included in a shunt ciredit l 31, with the condenser C and the l9 transmitter T, the latter deriving its current up ly direct from main battery through the choliecoil 2' by the circuit B, 20, 21, 22"and 1 ground. The third winding 71 is included in .40 the test circuit 11 and 28, which passes from g through to back contact on the relay to the tip conductor 5 and so on to the tip of the. callingplug P. Each cord cir- 1 cu'it. is equipped with a switching key O,

[ which corresponds to the ordinary ringing ,Lie'y in manual practice. Instead of the swims from this key leading to a" ringing generator, they lead directly to a pair of contacts on one of the relays controlling the So impulses from the sending machine. Each operator of course, is provided with a certain percentage of these cord circuits, enabling 'her to handle all incoming calls and to complate the connections for the same, and it of course follows that each operator will be provided with a set of these control relays, which can be made common to her-set of cords and plugs by means of the'switching key 0, with which each cord circuit is cocquipped; The sending machine itself can oficourse be c'ommon to the entire exchange,

L or it can be duplicated, it being only necessary to state that a set of keys and controlrelays are individual to each operator 66 an 'oomgnon to her connective apparatus.

' the circuits shown are the same as in the Letters Patent before referred to with the exception of placing the-relay G in place of the release magnet K In this case, the re- .leaserelay G? is first operated as though it also for controlling the ringin by applying the tip p of her plug P- to the thinibles 7' of successive jacks until the absence of a click indicates one which is idle.

Referring now to Fig. 3, I have shown circuits of a first selector, second selector and connector switches, as described in Letters Patent 815,321 and 815,176, granted. March 13,1906, to Keith and Erickson. I will not describe. these circuits in detail. The first selector switch X consists of the vertical relay D, .which when energized closes the circuit of-the vertical magnet V, which in turn causes the spindle 00, carrying the wipers to step up vertically. The rotary relay D, when energized operates the private relay F, causing the side switches to make one step. The rotary magnet L has its circuit closed after the side switches have made one move-- ment and will continue to vibrate, causing the spindle w to rotate until the test wiper finds a contact free from ground. As soon as thishappens, the side switches make still another movement, disconnecting the vertical and rotary relays from the trunk wires and closin the trunk wires themselves through tot e trunk wi ers. The last movement of the side switc es also connects the trunk release relay G to the test wiper. The magnet K is the release magnet and when operated restores the switch to its normal position. The'circuits of the second selector switch X are similar to those of the first selector switch and need not be described.

Referring now to the connector switch m were the release magnet and in turn closes the circuit of "the magnet K Instead of testing on athird wire or test wiper, I do the testing directly on one side of the line or trunk. In place of the ordinary back release. relays which were connected-ito the trunk wires 163 and 164, respectivelyfI have replaced with the release relays D and D with bridged battery between them for supplyingcurlent to the called subscriber and" relay Y. The ringing relay Y is energize when the sleeve relay D is energized and disconnected 'when'the tip relay 1) is operated, closing llhen the i essence the rotary rclay l) and the private relay F remain uurhangzed and the method of operating and releasing the switch is the same.

Referring now to 4e and I will describe the sending machine and its circulls. The drum or cylinder A is made up of 16 disks or punchings. The first of these disks from A to is inclusive are used for transmitting impulses to ope ate the various automatic switches. The disk A is provided with one tooth, the disk A with two teeth and so on up to disk 1- which is provided with 10 teeth. The next 5 disks A, A, A, 91 and it. are each provided with one tooth for controlling the set of relays shown in Fig. 2. By referring particularly to Fig. 2 it will be seen that the teeth are arranged synchronously on the periphery of the drum. By noting the direction the Wheels, travel, as indicated by the arrow, it Will be seen that the tooth on the Wheel A travels in advance of the teeth on the other wheels, and that the tooth on the wheel A. is in advance of the teeth on the remaining wheels. The

tooth on the Wheel A is in advance of the two remaining Wheels, while the tooth on the Wheel 1. 1s the last. The Wheel A controls the relay S while the wheel A. con trols the relay S.

itBfBI'IHlg to the mechanical ngures m Figs. l and 5, the remalnmg wheel or disk A. 1s provided with one tooth which is used for sending the rotary or switching impluse to the automatic switches. All of these disks, which can be made of any suitable material, preferably'of brass are bolted or clamped together by means of the bolts and nuts V. These disks are all fixed fast to the shaft W by means of a key or otherwise, which turns freely in the bushings W'f. These bushings are fixed firmly in the bra ckcts or braces so as to form suitable hearing for the shat-t. The braces themselves are fastened firmly to a base J by means of suitable bolts. A mounting plate ll] is fastened to these brackets and carries the springs which are operated by the teeth on the various disks. These springs are mounted like relay springs. each set of springs being separated by the insulating blocks W and clamped to the st 1 the screws il Each set oi springs, with the exception of the live which control the relays are normally open, While latter are. normally closed. These springs are operated by the teeth working the plungers bile the rum is rotating.

Referring now to Fig. 1?, it will be seen that one spring of the set a, is connected rc to the first button in each strip of heys. one spring of the set a to the second butt-on in each strip and so on up until. the ten sets are connected. to the ten buttons. hut-ton of any et or strip is mpulso at each will be 1 closed, one

Vi? by means of.

to the number of teeth on the wheel to which it is connected. The series of relays shown are for transmitting; these impulses in groups and in regular order so as to operate the automatic switches properly. The button c" is for starting the impulses after the proper buttons have been set up. This button. when depressed, closes the circuit of the relay S, which then closes the circuit of the relay S. The relay S closes the circuit of the relay S which closes the circuit of the relay S .and this relay in turn closes the circuit of the relay 3*. While these relays are all energized, the trunk wires 15 and 16 are closed'on to the extensions through the contact of the other relays, but as all of those 4 relays are energized. the common wires 120, 119. 118 and 117 leading to the strips of buttons are disconnected,.so 'of course no impulses can be transmitted. These relays, after the button 6 has been depressed, re main locked through the normally closed contacts (1 a, a", a and a. The relay S is only looked through the contacts a, but the. other relays, besides being locked throughjfthe contacts already mentioned are each locked through the contacts of the preceding relay, as plainly shown on the drawing. In other words, the relay S is the only one left unguarded. As soon as the tooth on the wheel A reaches the contact a. the relay S becomes deenergized and falling back, connects the common wire 117 to the the wirell:- by means of the number Wheel 1 A which is provided with 10 teeth. After one complete rotation, the relay S falls back as the contacts (1 are broken by the tooth on the wheel A; This relay is enabled to fall back now because the relay S is denergized and it is not guarded. The relay. S in falling back, opens the contacts 8 and s disconnecting the wire 117 from the trunk wire 15, and in its place connects the common wire 11$; belonging to the strip of buttons E. impulses Will now be sent over the common wire 118 through whichever button is down in the strip E The strip of buttons. "E tra-nsmits im pulses corresponding to the thousands and operates the first'sel ectorswitch. The strip oii buttons E transmits; the hundreds and operatesthe second. selector switch, while the strips E?" and the tons and back by the breaking of units and operate the connector switch. Af-

the relay S falls the contacts at by the tooth on the wheel A and disconnects the wire 118, and in its-place connects the common wire 119 leading to the strip E At the end of the third rotation, or beginnmg of the fourth, the relay S falls back by the breaking of the contacts a by the tooth on the wheel A. This relay falling back, disconnects the wire 119 and in its place connects the common Wire 120 leading to the strip of keys E After the fourth rotater the second rotation,

tion, or at the beginning of the fifth, the rei lay Stfalls back by the breaking of the contacts a by the tooth of the wheel A (See Fig. 6.) This relay in falling back disconnects the trunk wires 15 and 16.

from the last strip of keys, thereby preventing further impulses. At every rotation and immediately after each group of impulses a single impulse is sent to trunk wire 16 by the closing of the contacts a. This impulse is for operating or transferring the side switches in the various selector and connector switches. The lamp L has its circuit completed when the relay S is energized and remains lighted until a complete set of impulses-have been sent, or until the drum' makes four complete revolutions. This lamp remains lighted for the purpose of notifying the operator that the key set is busy and cannot be used until the lamp is extinguished. Y

In the drawing I have shown the springs a, a etc. in pairs, operated by the respective teeth on the drum, but I may obviously use single springs bearing'directly on the n'letallof the teeth, while the drum or frame can be connected directly to ground. This arrangement is shown in end elevation in Fig. 6, but I consider the arrangement of Figs. 4 and 5 preferable.

By referring to F igs..1 and 2, it will be noticed that the operators connective apparatus is connected to the sending device by means of the switching key 0. When the operator desires to complete a connection,- she'throws this keyfforward, depresses the proper buttons in the key set and then pushes the starting button and the impulses will then come from the trunk wires 15 and 16 to the connective apparatus and from there to the automatic switches in regular order. As soon as the lamp L is extlnguished, after the impulses have been sent,

the operator throws the switching key hack to its normal position. It is necessary to throw the key in this manner as I have already stated the keys and the relays are common'to the connective apparatus and if the key 0 were left thrown over, impulses would of course go over the trunk 'again whenshe is putting through. aacall on some 'other trunk. Of course if each cord circuit were provided with a set of controlling relays, it would be unnecessary to provide the switching key 0. g

The operation of my system is as follows: The subscriber at station A, desiring to make a call, removes his receiver, which closes the circuit of the relay M through the normally closed contacts of the relay M, the relay M operating closes the circuit of the signal lamp L The operator, upon getting this signal, inserts the plug P into the jack J, thereby placing the relays M and R in series. The relay M, in operating, disconnects the relay M, which upon falling back, extinguishes the lamp L, at the same time the relay M connects the trunk wires .1 and 2 to the extension leading directly to 1 Verse with the calling party. Upon getting the number desired, she picks up the plug P and tests for an idle trunk jack by means. of touching the tip of the plug P- to the thimble of the jacks J. When testing and touching the thimbles of busy jacks, she will receive a click through her receiver by .inductionthrough the third winding on the induction coil. Having found an idle trunk jack, she insertsthe plug P into the jack connected to that trunk. The insertion of the plug closes the circuit of the relay R in series with the resistance coil attached to the thimble of the jack. The energizing of the relay R opens the circuit of the relay R thereby disconnecting the operators telephone set from the tip and sleeve of the answering plug. The energizing of the relay R disconnects the third or test winding of the induction coil from the tip of the calling plug P. f

Suppose the number desired by the calling party was 1234; the operator at once depresses or sets up the following buttons on the key set: In the strip E she sets the first button 6; in the strip E the second button e; in the strip E the third button 6 in the strip E the fourth button e H aving set up the buttons corresponding to the number desired, she throws forward the switching key 0 and then depresses the lay S is kept looked through. the, contacts inserts o and contacts s and s of the relay S; the relay S is kept looked through the contacts o and through the contacts 8 and s of the relay'fifi, while the relay S is kept looked through the contacts a and the contacts 3 and s of the relay S The circuit of the lamp L is completed through thecon'tacts s and s of the relay 8*. As soon as the relay S falls back when the tooth on the wheel A opens the contacts a the circuit is closed from the common wire 11'? to the, tip of thetrunk and one impulse is sent thereon by the following path: ground, 115, a, 131, e, 117, a, s, 8 8 s", 8 8, s 5 .9 15, 0, 5, p, j to 105 side of the trunk leading to the first selector switch. This impulse closes the circuit of the relay D in the first selector switch X, causing the spindle carrying the wipers tostep up to the first row of contacts. After this impulse, a single impulse is sent to the opposite side of the trunk by the following path: ground, A

132, s 121, 8 8 is, 0, 3, 32', to 106 side'of the trunk. This impulse closes the circuit of the relay D in the first selector switch, which in turn closes the circuit of the private relay F, causing the side switches to take one step cutting on the rotary magnet I). This rotary magnet as well as the succeeding rotary magnet L has a circuit breaker or vibrator mechanism associated with its armature as indicated in the diagram by a pair of closed contacts between the coils, and an insulating wedge on the armature, adapted to separate them when it is pulled up on each vibration. Each magnet therefore constitutes in itself an automatic vibrator or buzzer. The operation of the rotary magnet L causes the switch to rotate and continue until the test wiper finds an idle contact leading to a second selector switch. As soon as this happens, the relay F falls back, causing the side switches to take another step, thereby disconnecting the rotary magnet L This last step connects the trunk wires directly to the trunk wipers leading to an idle second selector switch and also connects the trunk release relay G directly from ground to thetest wiper, rendering the switch busy for other calls.

Referring again to Fig. 2, after the first vertical and rotary impulses have been sent the drum starts its second rotation, breaking the contacts a, disconnecting the relayS. This relay in falling back disconnects the common ire 117 of the strip E from the wire 15 and in its place connects the common wire 118 of the strip Fl through the contacts s and a". Two impulses are now sent over the tip or vertical side of the trunk through the button 6 by means of the number wheel A These two impulses now close the circuit of the relay D in the second selector switch X, causing the swltch spindle carrying the wipers to step up yertically to the second row. After this group of im-v pulses, a single rotary impulse is sent as before and operates the relay D which in turn closes the circuit ofthe relay F, causipg the side switches to take one step cutting on the rotary magnet L Under the influence of this magnet the spindle rotates until the test wiper finds an idle contact whereupon the relay F becomes deenere gized and causes the side switches to take another step. This last step of the side s itches disconnects the rotary magnet L and connects the trunk release relayvG directly from ground to the test Wiper and .also closes the trunk wires to the trunk wipers leading to an idle connector switch.

After the second group or set of impulses ,have been'sent, the drum starts its thirdrotation thereby opening the circuit of the relay S at the contacts a. This relay falling back disconnects the common wire 118 of the strip E from the wire 15 and in its place connects the common wire 119 of the strip E Three impulses are now sent over the vertical side of the trunk through-the button c by means of the number wheel A These impulses close the circuit of the relay D*, which in turn closes the circuit of the vertical magnet V causing the spindle carrying the wipers to step up to the third row of contacts. After this set of impulses, a rotary impulse is sent over the opposite side of the trunk through the contacts a as before operating the relay D which in turn closes the circuit of the relay F causing the side switches to take one step, disconnecting the vertical magnet V and in its place connecting the rotary magnet L This movement of the side switches also connects the test relay G to the tip of the trunk through the. normally open contacts of the relay F A ter this third group of impulses. and at the beginning of the fourth rotation, the re lay S has its circuit open at a and in falling back disconnects the common wire 119 of the strip E and in its-place connects the common wire 120 of the strip E Four i1n' pulses are now sent over the vertical side of the trunk through the button 6 by means of the number wheel A These impulses operate the relay D which in turn closes the circuit of the rotary magnet L which causes the switch to operate and bring the wipers to rest on contacts leading to the desired line, which in this case is the fourth set. After this set of impulses a single ro'- tary impulse is sent over the opposite side of the trunk, closing the circuit of the relay D which in turn closes the circuit of the re lay F thereby connecting the test relay G to the tip side of the trunk or line. If the line is busy, the relay G becomes energized 'and closes the circuit of the magnet K which restores the switch to its normal position. it the line is not busy, as we will suppose to be the case, the relay Gr fails to get current and the side switches take another 1 step, disconnecting the rotary magnet and test relay and connects the trunk wires through to the trunk wipers leading to terminals of the desired line. As soon as this condition is brought about, the relay D is placed in series with the line out ofl' relay as in Fig. 1. The relay D thereupon closes the circuitof the ringing relay Y by the following path: battery- B, d d d d Y; commutator to ground. By means of this commutator, generator current is sent out intermittently over the called line, thereby ringing the subscribers bell. When the called subscriber answers, the relay I) becomes energized, when the ringing relay Y is deenergized. The operating of this relay closes the circuit of the relay D which re mains looked through the contacts :0 and w. The locking of this relay disconnects the ringing relay Y and prevents its operating in case the called party should hang 'up his telephone first.

Referring again to Fig. 2, after the fourth set or group of impulses have been sent, the drum starting on its fifth rotation, opens the circuit of the relay S throughthe contacts a. This relay, in dropping back, disconnects the wires 15 and 16 from the common wires 120 and 132 respectively, thus preventin further impulses being sent. The relay g in italling back, also extinguishes the lamp L notifying the operator that the call has been completed. Upon getting this signal, she restores the switching key 0, thereby severing the wires 15 and 16, from the wires 5 and .6. At the hend of the conver sation the callin party anging up, opens the ciicuit of tli e relay B, Fig. 1, which upon falling back, closes the circuit of the supervisory lamp L, notifying the operator thatthe parties have finished talking. This relay R, in falling back, also connects ground to both sides of the trunk through the contacts 1' 'and r of the relay R. Ground being thus placed on both sides of 4 the trunk at the same time closes the circuits of the relays D and D in the connector switch, efi'ecting its release and also releas ing the first and second selector switches in the following manner: The operating of the relays D and .D simultaneously'places the relays G and G in series. The operating of the relay Gr closes the circuit of the magnet K, thereby restoring the connector switch X to its normal position. The op,- erating of the relay G in the second selector switch, places the magnet .K' in serieswlth the relay G in the first selector switch. The

operating of the magnet K restores the sec- 0nd selector switch X, while the relay G closes the circuit of the magnet K, thereby restoring the'first selector X. When the connector switch is restored the contacts 112 and w are broken, unlocking the relay 1). Referring to Fig. l, the operator getting the disconnect signal, withdraws the plug P from the answering jack J and the calling plug P from the trunk jack J, thereby restoring all parts to their normal condition. It is tobe understood that the description herein is made specific for purposes of definition and not of limitation, and I contemplate all non-essential changes and substitutions such as a solid drum withv continuou tooth project-ions, or the like, which fair fall within the scope of the appended claims. Having thus described my invention what I claim and desire to secure by Letters Patent is- 1. An. electrical transmitter comprising a drum having ten circular groups of teeth netically controlled selective means connected thereto to send impulses through" the respective groups of keys during successive rotations of the drum, one digital group of impulses only for each complete rotation.

2. An electrical transmitter comprising adrum having ten circular groups of-teeth in consecutive order from one to ten, ten contact devicescooperating with said teeth, ten circuit wires extending from said contact devices to a plurality of groups of se lecting keys, each group containing tenkeys connected to the respective wires in the same order from one to ten, a plurality of teeth arranged in helical. order on a portion of the drum following the impulse teeth, with a corresponding plurality of relays controlling the circuit connections from'the respective groupsof keys to the transmission circuit, said relays being operated in succession, one only during each rotation of the drum, whereby a plurality of digits are transmitted by and during a corresponding plurality of complete rotations of the drum.

3. An electrical transmitter comprising a drum having ten circular groups of teeth in consecutive order from one to ten, ten contact devices cooperating with said teeth, ten

order from. one to ten,'a plurality .of 0011-.

trollingteeth on the drum with corresponding. contact devices, switching means for the several-groups of keys adapted tojoperatively connect one group only during each rotation of the drum, for transmission purposes, and. electromagnetic controlling means for said switching means, adapted to receive current at the end of each rotation only, through the contact devices of the controlling teeth on the drum.

4. An electrical transmitter comprising a drum having ten circular groups of teeth in consecutive order, from one to ten, whereby only one digit from one to ten is transmitted at each rotation of the drum, ten contact devices cooperating with said teeth, ten circuit wires extending from said contact devices to a plurality of groups of selecting keys, each group containing ten keys connected to the respective wires in the same order from one to ten, a plurality of-teeth arranged in helical order on a portion of the drum following the impulse teeth, with a corresponding plurality of relays 'controlling the circuitconnections from the respective groups of keys to the transmission circuit, one of said relays having its circuit controlled by each of said teeth, and means for rendering only one relay at a time ,operative, during each complete rotation of the drum, so as to correspondingly render only one. group of keys at a time operative during said rotation, and so as to require a plurality of rotations to send a corresponding plurality of digits.

5. A- number transmitter for multiple digit signaling system comprising a shaft, 85.

a plurality of contact devices corresponding' in number to the hlghest digit to be v transmitted arranged and held in operative relation to said shaft, the highest number sets of projections or teeth on said shaft arranged so that the said contact devices for each revolution of the shaft will receive impulses varying in number from the highest digit for the first-contact device to me lowest digit for the last one, means for selecting impulses from one of said contact devices during each of two or more rotations of the shaft, and interlocking means for the elements of the selecting means, controlled at the end of each rotation of the shaft to advance only one step at a time, and thereby permit the transmission of only one digit at a time or during a single rotation.

6. An electrical transmitter comprising a drum having ten circular groups of teeth in teeth, a relay for each pair of contacts, said relay controlling the connection of the keys to the transmission circuit, an energizing circuit for each relay except the first con: trolled by the preceding relay, independent means for controlling the energizing circuit of the first relay, and a locking circuit for each relay corresponding to and controlled by its corresponding contacts on the drum, whereby all the relays are set up and locked for multiple digit transmission, and one at a time released,at each rotation of the drum,the first relay released connecting its own group of keys but no others to the transmission circuit,- during the first rotation, the second relay released similarly connecting its group of keys and no other during the second rotation, and so on.

In testimony whereof I aflix my signature in presence of two witnesses.

JOSEPH LANE WRIGHT.

Witnesses:

J. C. MULLEN, DE F0 E. Moon. 

